The present invention relates to substantially horizontal hermetic compressors, and more particularly to the compressor housings and the mounting of components such as the terminal assembly, a sight glass, and a heater in the housing.
In general, the housing of a substantially horizontal hermetic compressor may include a substantially cylindrical main body portion and a pair of end caps mounted to each end of the main body portion. Alternatively, one of the end caps may be integrally formed with the main body portion. A motor and a compression mechanism are mounted in the main body portion. The motor has a plurality of lead wires electrically connected thereto. The lead wires are then electrically connected to a terminal assembly mounted in the compressor housing. The terminal assembly is electrically connected to an external power source to provide the motor with electrical current.
An oil sump is formed in the lower portion of the compressor housing. Components, such as a sight glass or heater, may be mounted in the compressor housing to be in communication with oil in the oil sump. The sight glass is mounted in the housing at a position where the oil in the sump is visible. This allows the operator to visually determine whether there is sufficient oil in the compressor.
A heater may be mounted in the housing to warm the oil in the sump, to facilitate startup under cold conditions and prevent conditions such as foaming. Typically, after shutdown of the compressor, the pressure and temperature of the refrigerant vapor and oil in the compressor housing equalize and tend to mix. Upon startup of the compressor, the temperature and pressure increase and the mixture is agitated, causing the mixture to foam, limiting the amount of oil available to the compressor components. The heater is provided to maintain the temperature of the oil at a level different than that of the refrigerant after shutdown. By maintaining different oil and refrigerant temperatures, foaming upon startup of the compressor is prevented. Additionally, the viscosity of the oil increases as the temperature in the compressor housing decreases, causing the oil to resist flowing easily upon startup. By heating the oil, the viscosity of the oil can be controlled to more desirable levels.
The components typically mounted in the compressor housing include the terminal assembly, and perhaps a sight glass and/or a heater. In previous compressors, at least one of these components is mounted in the substantially cylindrical main body portion of the compressor housing. In order for the component to sealingly engage the outer surface of the housing main body portion, a flat, raised portion is formed therein. The flat, raised portion is provided with an aperture to receive the component and the flat surface defined by the raised portion provides a sealing surface to which the component is secured.
A problem with this type of housing construction includes mounting the components in different portions of the housing. For example, at least one component is mounted in the main body portion and at least one component is mounted in an end cap. Multiple assembly and welding operations are then required on different housing portions, which increases the complexity of assembly and thus the cost of assembly of the compressor.
Additionally, in order to accommodate components in the main body portion of the housing, modifications to the substantially cylindrical main body portion must be made to accommodate component mounting. For example, if above-described apertured, flat surface is not provided, sealing of the component to the cylindrical main body portion may be difficult to achieve, and may result in a potential leakage point in the housing. Further, manufacturing of the main body portion to accommodate the components is often complex, time consuming and expensive.
Further, the motor and/or the compression mechanism may be shrink-fitted into the cylindrical main body portion of the housing. During the shrink-fit operation, distortion of the main body portion at locations where these components are mounted may occur, creating problems during or after compressor assembly. Additionally, expansion and contraction of the main body portion during the shrink-fit operation may cause the housing to crack near the mounted components, necessitating scrapping or repairing the housing.